Pest risk assessment of wild oats in Norway

Wild oats (Avena fatua L.) are widely spread and constitute a weed problem in Norway. Wild oats compete strongly with cereal crops because of their similar biology and growth habit, and the weed can cause significant crop yield losses when left unmanaged.

The Norwegian Scientific Committee for Food Safety (VKM) has on request delivered a pest risk assessment of wild oats to the Norwegian Food Safety Authority (Mattilsynet). VKM was also asked to make an assessment of the probability that other species than A. fatua (other wild oats species with saucer-shaped abscission scar) can establish as a weed in Norway.

Pest risk assessment of wild oats (A. fatua L.)

Panel on Plant Health concludes that wild oats (A. fatua) is present in 155 out of 431 Norwegian municipalities. It is widely distributed in all municipalities in the main agricultural areas in south-east and central-east Norway, and in the municipalities close to the Trondheim fjord.

So far A. fatua is the only wild oats species that constitutes a weed problem in Norway.

Endangered area, not yet infested by A. fatua, is estimated to 228858 ha. This area is spread over the cereal growing part of Norway. The counties of North- and South-Trøndelag have a higher portion of endangered area not yet infested than southern and central part of East Norway.

The probability of entry of A. fatua from outside Norway is very low.

The probability of spread within Norway is high. In areas with low infestation, like in Trøndelag, the probability of spread is lower than in heavily infested areas. However, in areas with high level of infestation there are few new farms left to be infested.

Probability of establishment of other wild oats species

The main Avena species that are important weeds of cereal and arable crops include A. fatua L., A. sterilis and A. barbata Pott. All three species have an abscission scar on the grains.

For both A. sterilis ssp. macrocarpa and ssp. maxima, and for A. barbata Pott, the potential for entry and establishment in Norway is considered as very low. A. sterilis ssp. ludoviciana (winter wild oats) has a moderate potential for establishment in Norway.

The suitability of the environment for A. sterilis ssp. ludoviciana was therefore investigated:

The climate in Norway is considered as not favourable for establishment of A. sterilis ssp. ludoviciana. It is therefore not likely that it will become a weed in Norway under current conditions.

If the future climate of the PRA area changes, so that winter conditions become similar to conditions in southern England, while the acreage of winter cereal continues to grow, A. sterilis ssp. ludoviciana could become a weed in Norway

A. sterilis ssp. ludoviciana is not present in Denmark where winter cereals are much more widely cultivated. The climate is more favourable in Denmark than in Norway. One would therefore expect the weed to establish in Denmark before it will become a problem in Norway